Pressure sensors have been used for any number of applications in the past. In use, however, certain drawbacks arise depending on the many applications in which the sensor is used. Previously sensors were not completely isolated. As a result there was generally no means to prevent exposure of the sensor internal mechanisms to often harmful and destructive environments such as salt water.
Moreover, when isolated, these sensors were often unable to transmit the sensed force in a manner which accurately reflected the force as initially sensed by the transducer. Previous sensors have generally also not been equipped to prevent overactivation or overpressure forces which often destroy the sensors.
Sensors previously developed in this field include Delmonte, U.S. Pat. No. 3,427,884, which discloses a diaphragm element having a flexible tubular support wall or and an exposed thin flexible diaphragm that extends transversely across the support wall. Gealt, U.S. Pat. No. 4,006,640, discloses a pressure to current transmitter having an internal fluid chamber separated from the process fluid by a diaphragm and backup plate. Davis et al, U.S. Pat. No. 4,184,189, disclose an inexpensive glass capacitive pressure sensor. Sikorra, U.S. Pat. No. 4,196,632, discloses the apparatus including first and second support elements of fused quartz and an intermediately positioned thin diaphragm of the same material.
Nagasu et al, U.S. Pat. No. 4,321,578, disclose a dual sided pressure transducer arranged to hold a semiconductor pressure sensor in a housing. Wamstad, U.S. Pat. No. 4,399,707, discloses a stress sensitive semiconductor die and housing comprising a recessed ceramic base.
Marks et al, U.S. Pat. No. 4,600,912, disclose a diaphragm-type pressure sensor employing a monocrystalline wafer as a pressure-responsive diaphragm. Grantham et al, U.S. Pat. No. 4,467,394, disclose a three plate silicon-glass-silicon capacitive pressure transducer.
While these patents disclose pressure sensors and sensor elements which advance this field of technology, the previously mentioned problems still exist and are satisfied by the present invention.